Run Elasticsearch-dependent tests also in CI

[Pfeil]

Is your feature request related to a problem? Please describe.

We have a few deactivated tests for Elasticsearch which currently need to be run manually.

Describe the solution you'd like

There is a simple solution to have an ES container spawned just for testing, using this in the build gradle file:

    testImplementation "org.testcontainers:testcontainers:1.20.0"
    testImplementation "org.testcontainers:junit-jupiter:1.20.0"
    testImplementation "org.testcontainers:elasticsearch:1.20.0"

But: It has to be tested if this actually works in the GitHub CI.

Describe alternatives you've considered

Boring scripts, lame mocking, ...

Additional context